FPSC Everyday Science MCQs

The iris changes the size of the pupil.
This regulates how much light enters the eye.

Evaporation occurs at the surface of a liquid.
Higher temperature and moving air usually increase its rate.

The lens focuses incoming light onto the retina.
Photoreceptor cells then convert light into nerve signals.

Condensation occurs when gas particles lose energy.
Water vapor condenses into droplets on a cool surface.

Red light has the longest wavelength in the visible spectrum.
Violet has the shortest visible wavelength.

The highest-energy water molecules escape during evaporation.
This lowers the average energy and temperature of the skin.

Violet light has the shortest wavelength among visible colors.
It also has the highest visible-light frequency.

Wind carries away water vapor near the fabric.
This maintains a concentration difference and speeds evaporation.

Rayleigh scattering is stronger for shorter visible wavelengths.
Scattered blue light reaches observers from many directions.

At boiling, vapor bubbles form throughout the liquid.
It occurs when vapor pressure matches external pressure.

Sunlight travels through more atmosphere near the horizon.
Much of the shorter-wavelength light is scattered away.

Atmospheric pressure decreases with altitude.
Lower pressure allows water to boil at a lower temperature.